JP2019065763A - Centrifugal fan - Google Patents

Abstract

To provide technique capable of reducing the size and the thickness of a centrifugal fan.SOLUTION: A centrifugal fan 100 includes a motor 30, an impeller 10, a circuit board 40, and a casing 1. The casing includes a lower casing 3 having a board storage part recessed to an axial lower side so as to store the circuit board therein. The impeller includes a boss, a plurality of blades, an upper shroud, and a lower shroud. The boss is fixed by a rotor 32. The blades are arranged on an outer peripheral surface of the boss at intervals in a circumferential direction, and extend to a radial outer side. The upper shroud connects at least a part of an axial upper side of the blade. The lower shroud connects at least a part of an axial lower side of the blade. At least a part of a lower end surface of the blade faces an upper surface of the circuit board in an axial direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a centrifugal fan.

  The centrifugal fan is disclosed by Unexamined-Japanese-Patent No. 2016-106197. The centrifugal fan has a structure in which an impeller having a plurality of blades circumferentially arranged between an upper casing and a lower casing in which an air suction port is formed is housed. The centrifugal fan discharges the air introduced through the opening to the side of the impeller as the impeller rotates. The lower casing is made of a metal plate and has a recess that is recessed downward. A motor is attached to the bottom of the recess. A portion of the motor stator and the circuit board on which the motor drive circuit is mounted are housed inside the recess. The recess is provided with a hole through which means for supplying power to rotate the motor pass.

JP, 2016-106197, A

  In the configuration in which the impeller blade portion of the impeller is sandwiched between the upper shroud and the lower shroud as in Patent Document 1, when the impeller is formed by a single member, a mold lateral slide mechanism is required, and the mold structure is complicated. Turn In addition, there is a restriction that the undercut portion near the intake port can not be provided. On the other hand, when the impeller is made of two parts, it is possible to solve the geometrical problem that is a problem when molding with a single part. However, since two molds are required and a construction method such as welding for fastening two members is required, the degree of difficulty of manufacture becomes high. Therefore, it is preferable to mold the structure of the impeller with a single member as a structure that allows the mold to be pulled up and down.

  On the other hand, there is a demand to enlarge the circuit board in accordance with the increase in size of the electronic components in order to increase the size of the electronic components to be used in the high output motor. In the case of enlarging the circuit board with the configuration of Patent Document 1, it is necessary to enlarge the recess for housing the circuit board. As a result, a space is created between the peripheral portion of the recess and the impeller, and the air guiding function of the lower casing is lost. As described above, when the circuit board is enlarged, the static pressure characteristic, the air volume characteristic, and the noise characteristic may be deteriorated.

  As a countermeasure for this, it is also conceivable to fill the space between the peripheral portion of the recess and the impeller by extending the lower shroud of the impeller radially outward. However, this method has a problem that undercuts occur in the upper and lower shrouds, and the mold structure becomes complicated. In addition, the height of the blade portion may be shortened, and the air volume may be reduced in the thin centrifugal fan.

  An object of the present invention is to provide a centrifugal fan excellent in static pressure characteristics and air volume characteristics when the circuit board is enlarged, and small in noise, with a configuration suitable for downsizing and thinning.

  An exemplary centrifugal fan of the present invention comprises a motor having a stator and a rotor rotatable relative to the stator, an impeller fixed to the rotor and rotating with the rotor, and electrically connected to the motor A centrifugal fan having a circuit board to be mounted, the motor, the impeller, and a casing for accommodating the circuit board, wherein the casing is recessed axially downward, and the substrate accommodating portion for accommodating the circuit board The impeller is disposed circumferentially spaced from the cylindrical boss portion fixed to the rotor and the outer peripheral surface of the boss portion, and the impeller is directed radially outward A plurality of extending vanes, an annular upper shroud connecting at least a part of the axial upper side of the vanes, and an annular connecting the lower side at least axially of the vanes It has a lower shroud, the at least a portion of the lower end surface of the blade portion, opposite the upper surface and the axial direction of the circuit board, a centrifugal fan.

  According to the present invention, it is possible to provide a technique for reducing the size and thickness of a centrifugal fan.

FIG. 1 is an external perspective view showing an entire configuration of a centrifugal fan according to an embodiment of the present invention. FIG. 2 is a side cross-sectional view of a centrifugal fan according to an embodiment of the present invention. FIG. 3 is a perspective view showing a state in which the upper casing and the impeller are removed from the centrifugal fan. FIG. 4 is a perspective view of the impeller as viewed from above. FIG. 5 is a perspective view of the impeller as viewed from below. FIG. 6 is a partial cross-sectional view around the exhaust port of the centrifugal fan according to the embodiment of the present invention. 7 is an enlarged view of the upper and lower shrouds of the impeller in FIG. FIG. 8 is an enlarged view of the facing portion of the impeller and the circuit board in FIG.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In this specification, a direction parallel to the central axis P of the centrifugal fan 100 shown in FIG. 2 is “axial direction”, a direction orthogonal to the central axis P is “radial direction”, and an arc centered on the central axis P The direction along is called "circumferential direction", respectively. Further, in the present specification, the direction in which the central axis P extends is the vertical direction, and the shape and positional relationship of each part will be described with the impeller 10 side as the upward direction and the motor 30 side as the downward direction. However, there is no intention to limit the use direction of the centrifugal fan 100 according to the present invention based on the definition in the vertical direction.

  Further, in the present application, the “parallel direction” also includes a substantially parallel direction. Further, in the present application, the “orthogonal direction” also includes a substantially orthogonal direction.

<1. Configuration of centrifugal fan>
FIG. 1 is an external perspective view showing an entire configuration of a centrifugal fan 100 according to an embodiment of the present invention. FIG. 2 is a side cross-sectional view of a centrifugal fan 100 according to an embodiment of the present invention. FIG. 3 is a perspective view showing the centrifugal fan 100 from which the upper casing 2 and the impeller 10 are removed. As shown in FIGS. 1 and 2, the centrifugal fan 100 has a casing 1, an impeller 10, a motor 30, and a circuit board 40.

  The casing 1 accommodates the impeller 10, the motor 30, and the circuit board 40. The casing 1 has an upper casing 2 and a lower casing 3. The upper casing 2 covers the axial upper side of the impeller 10 and has a circular air inlet 2 a facing the radial center of the impeller 10. The lower casing 3 accommodates the motor 30 and the circuit board 40. The lower casing 3 has a substrate housing portion 4 and a flange portion 5 extending radially outward from the peripheral edge of the substrate housing portion 4. The board accommodation portion 4 is recessed downward in the axial direction, and accommodates the circuit board 40. The board accommodation portion 4 has the same shape as the circuit board 40 and is formed slightly larger in the radial direction than the circuit board 40. A motor 30 is positioned at a radial center of the board accommodation portion 4, and a circuit board 40 is disposed around the motor 30.

  The motor 30 has a stator 31, a rotor 32, a shaft 33, a bearing 34, and a bearing holder 35. The rotor 32 is disposed above the stator 31 and radially outward. The rotor 32 is in the form of a cup that opens downward. The impeller 10 is fixed to the outside of the rotor 32. The shaft 33 is fixed at the radial center of the rotor 32. A rotor magnet 36 is fixed to the inner circumferential surface of the rotor 32. In the present embodiment, the rotor magnet 36 is a single annular magnet. An N pole and an S pole are alternately magnetized in the circumferential direction on the radially inner surface of the rotor magnet 36. A plurality of magnets may be disposed on the inner circumferential surface of the rotor 32 instead of a single annular magnet.

  The shaft 33 is a columnar member disposed along the central axis P. As a material of the shaft 33, for example, a metal such as stainless steel is used. The upper end portion of the shaft 33 is located above the upper bearing portion 34. The upper end portion of the shaft 33 is fixed to a rotor hole axially penetrating along the central axis P of the rotor 32.

  The bearing portion 34 rotatably supports the shaft 33 about the central axis P. The bearing holder 35 supports the stator 31 radially outward and supports the bearing 34 radially inward. As a material of the bearing holding portion 35, for example, a metal such as stainless steel or brass is used. However, the material of the bearing holding portion 35 is not limited to metal, and may be resin. The bearing holding portion 35 axially extends in a cylindrical shape around the central axis P. The lower end portion of the bearing holding portion 35 is inserted into a circular hole provided on the central axis P of the lower casing 3 and fixed to the lower casing 3.

  The stator 31 is an armature that generates a magnetic flux according to the drive current. The stator 31 has a stator core, an insulator, and a coil.

  The stator core is a magnetic body. For example, laminated steel plates are used for the stator core. The stator core has an annular core back and a plurality of teeth. The core back is fixed to the outer peripheral surface of the bearing holder 35. The plurality of teeth project radially outward from the core back. The insulator is an insulator. For example, resin is used as a material of the insulator. The insulator covers at least a part of the stator core. A coil consists of a conducting wire wound around teeth via an insulator.

  By supplying a drive current to the stator 31, a rotational torque is generated between the rotor magnet 36 and the stator 31. Thereby, the rotor 32 rotates with respect to the stator 31, and the impeller 10 fixed to the rotor 32 also rotates around the central axis P. The motor 30 illustrated in FIG. 2 is an outer rotor type motor in which the rotor 32 is disposed on the radially outer side of the stator 31, but of the inner rotor type in which the rotor 32 is disposed on the radially inner side of the stator 31. It may be a motor.

  The circuit board 40 is electrically connected to the motor 30 and supported radially outward of the motor 30. The circuit board 40 is disposed in the board housing portion 4 of the lower casing 3. The circuit board 40 is disposed substantially perpendicularly to the central axis P on the upper side of the lower casing 3 and the lower side of the stator 31. The circuit board 40 is fixed to, for example, an insulator. On the circuit board 40, an electric circuit for supplying a drive current to the coil is mounted. The ends of the conductive wires constituting the coil are electrically connected to the terminals provided on the circuit board 40.

  FIG. 4 is a perspective view of the impeller 10 as viewed from above. FIG. 5 is a perspective view of the impeller 10 as viewed from below. The impeller 10 includes a boss 11, a plurality of blades 13, an upper shroud 15, and a lower shroud 17. The boss portion 11, the blade portion 13, the upper shroud 15, and the lower shroud 17 are single members formed of the same resin material.

  The boss portion 11 has a cylindrical shape, and is fixed to the outer peripheral surface of the rotor 32 on the upper side of the motor 30. The plurality of blade portions 13 are arranged at intervals in the circumferential direction from the outer peripheral surface of the boss portion 11. The vanes 13 radially extend outward in the radial direction while being inclined in the same direction as the rotational direction of the centrifugal fan 100 in a plan view. The direction in which the vanes 13 extend radially outward is not limited to this. A part of the vanes 13 may extend in the direction opposite to the rotational direction, or may extend orthogonal to the rotational direction.

  The upper shroud 15 is annularly provided so as to connect at least a part of the upper side of the blade portion 13, specifically, a radially outer portion. The lower shroud 17 is annularly provided so as to connect at least a portion of the lower side of the blade portion 13, specifically, a radially inner portion.

  The gas sucked from the intake port 2a of the upper casing 2 is circumferentially swirled in the casing 1 by the rotation of the impeller 10, and then discharged from the exhaust port 2b provided between the upper casing 2 and the lower casing 3 Ru. The upper shroud 15 and the lower shroud 17 improve the fan efficiency of the centrifugal fan 100 by efficiently guiding the gas drawn into the casing 1 from the air inlet 2a to the air outlet 2b. The exhaust port 2 b is provided in the entire circumferential direction of the casing 1. However, the exhaust port 2 b may be provided only in a part of the casing 1 in the circumferential direction.

<2. Configuration around the exhaust port of centrifugal fan>
Next, the configuration around the exhaust port 2b, which is a characteristic part of the centrifugal fan 100 according to the present embodiment, will be described in detail. FIG. 6 is a partial cross-sectional view of the vicinity of the exhaust port 2 b of the centrifugal fan 100 according to the embodiment of the present invention. FIG. 7 is an enlarged view of the upper shroud 15 and the lower shroud 17 of the impeller 10 in FIG.

  As shown in FIG. 6, the rotor 32, the boss portion 11 and the blade portion 13 of the impeller 10 are arranged to overlap in the radial direction. The lower end surface of the rotor 32 and the lower end surface of the boss portion 11 are located axially above the lower end surface 13 a of the blade portion 13. Furthermore, by keeping the axial height of the boss portion 11 within the axial height of the impeller 10, the centrifugal fan 100 can be thinned. Furthermore, the axial heights of the stator 3 and the rotor magnet 36 are accommodated within the axial height of the impeller 10. Thereby, the centrifugal fan 100 can be thinned.

  In the impeller 10, at least a portion of the lower end surface 13a of the blade portion 13, specifically, a radially inner portion of the lower end surface 13a of the blade portion 13 axially faces the upper surface 40a of the circuit board 40. Thus, the air flow axially introduced from the gap between the air inlet 2 a and the outer peripheral surface of the boss portion 11 and the inner peripheral surface of the upper shroud 15 is guided in the centrifugal direction along the upper surface 40 a of the circuit board 40. That is, when the upper surface 40a of the circuit board 40 doubles as a part of the flow path of the air flow, the casing 1 can be thinned.

  As shown in FIG. 7, the radially outer end 17 a of the lower shroud 17 is located radially inward of the radially outer end 40 b of the circuit board 40. As a result, as shown by the black arrows in FIG. 6, the air flow that has flowed in along the lower shroud 17 from the intake port 2a further turns in the centrifugal direction on the upper surface 40a of the circuit board 40 and is discharged from the exhaust port 2b Ru.

  Further, the upper surface 5 a of the flange portion 5 of the lower casing 3 has the same axial height as the upper surface 40 a of the circuit board 40. Thereby, since the upper surface 5a of the flange portion 5 and the upper surface 40a of the circuit board 40 are positioned on the same plane, the air flow can be smoothly discharged in the centrifugal direction along the circuit board 40 and the flange portion 5. The upper surface 5 a of the flange portion 5 may be lower than the upper surface 40 a of the circuit board 40. In this case, it is possible to suppress the air flow, which has been turned in the centrifugal direction along the upper surface 40 a of the circuit board 40, from being attenuated against the radially inner end 5 b of the flange portion 5. That is, the height of the upper surface 5 a of the flange portion 5 may be equal to or less than the height of the upper surface 40 a of the circuit board 40.

  For example, a plurality of electronic components are disposed on the lower surface of the circuit board 40 facing in the axial direction. A radially inner end 5b of the flange portion 5 and a radially outer end 40b of the circuit board are opposed to each other with a predetermined gap 50 therebetween. The space on the upper side in the axial direction of the circuit board 40 in which the impeller 10 is disposed communicates with the space in the board accommodation portion 4 located on the lower side in the axial direction of the circuit board 40 via the gap 50. As a result, the air flow which has been turned in the centrifugal direction along the lower shroud 17 and the circuit board 40 passes through the gap 50 and enters the space in the board housing portion 4 between the circuit board 40 and the lower casing 3. To flow. Therefore, the electronic components mounted on the lower surface of the circuit board 40 can be cooled. Thus, the heat generation of the electronic component can be suppressed.

  Further, at least a portion of the lower end surface 13 a of the blade portion 13, specifically, a radially outer portion of the lower end surface 13 a of the blade portion 13 axially faces the upper surface 5 a of the flange portion 5. That is, the lower end surface 13 a of the blade portion 13 is axially opposed to the upper surface 40 a of the circuit board 40 and the upper surface 5 a of the flange portion 5. The upper surface 40 a of the circuit board 40 and the upper surface 5 a of the flange portion 5 are continuously and horizontally arranged, and the blade portion 13 is arranged above the upper surface 40 a of the circuit board 40 and the upper surface 5 a of the flange portion 5. By extending the blade portion 13 to a position overlapping the flange portion 5 in the axial direction, the amount of air generated by the rotation of the impeller 10 can be increased.

  The lower shroud 17 has an inclined portion 17 b and a flat portion 17 c. The radially inner end of the inclined portion 17 b is connected to the outer peripheral surface of the boss portion 11. The inclined portion 17 b inclines downward from the radially inner side to the outer side. The flat portion 17c is continuously formed on the radially outer side of the inclined portion 17b, and extends along a plane perpendicular to the axial direction. By the lower shroud 17 having the inclined portion 17b, the air flow that has flowed in in the axial direction from the air inlet 2a can be directed to the upper surface of the circuit board 40 along the inclined portion 17b. Further, by providing the flat portion 17c continuously to the sloped portion 17b, the direction of the air flow can be smoothly changed in the centrifugal direction along the sloped portion 17b, the flat portion 17c, and the circuit board 40.

  The radially outer edge 17 a of the lower shroud 17 is at the same position in the radial direction as the radially inner edge 15 a of the upper shroud 15. Thereby, when injection molding of the impeller 10 with resin is carried out, a metal mold can be pulled up and down. Therefore, there is no need to split the mold or to provide a slide mechanism of the mold, and the structure or manufacturing process of the mold can be simplified. The radially outer edge 17 a of the lower shroud 17 may be radially inner than the radially inner edge 15 a of the upper shroud 15. That is, the radially outer edge 17 a of the lower shroud 17 is at the same position in the radial direction as the radially inner edge 15 a of the upper shroud 15 or radially inner than the radially inner edge 15 a of the upper shroud 15 If so, the mold can be removed in the vertical direction.

  In order to simplify the mold structure or manufacturing process of the impeller 10, the positional relationship between the radially outer edge 17a of the lower shroud 17 and the radially inner edge 15a of the upper shroud 15 is as described above. Thus, the radial length from the central axis P to the radially outer edge 17 a of the lower shroud 17 is shortened, and the smooth flow of air in the centrifugal direction is restricted. However, in the present embodiment, when the lower end surface 13 a of the blade portion 13 axially faces the upper surface 40 a of the circuit board 40, the airflow flowing in the axial direction from the intake port 2 a is the upper surface 40 a of the circuit board 40. Guided in the centrifugal direction. That is, when the upper surface 40a of the circuit board 40 doubles as a part of the flow path of the air flow, the casing 1 can be thinned.

  FIG. 8 is an enlarged view of the facing portion of the impeller 10 and the circuit board 40 in FIG. The electronic component 60 is mounted on the circuit board 40 at a position radially outward of the radially outer edge 17 a of the lower shroud 17. As a result, the electronic component 60 is disposed in the flow path of the air flow induced in the centrifugal direction along the lower shroud 17, and the air flow effect of the electronic part 60 is achieved. In particular, the heat dissipation amount from the electronic component 60 can be reduced by arranging the electronic component 60 having a large calorific value at a position radially outward of the edge 17a.

  Further, by arranging the upper casing 2 above the upper shroud 15, the disturbance of the air flow around the upper shroud 15 is suppressed, and the efficiency of the centrifugal fan 100 is improved.

  Various technical features disclosed in the present specification can be variously modified without departing from the spirit of the technical creation. In addition, the plurality of embodiments and modifications shown in the present specification may be implemented in combination as far as possible.

  The present invention can be used, for example, for a range hood fan, a ventilation fan for a duct, a heat exchange unit, and a centrifugal fan used for sheet adsorption of a printing apparatus.

DESCRIPTION OF SYMBOLS 1 ... Casing 2 ... Upper casing 3 ... Lower casing 4 ... Substrate accommodating part 5 ... Flange part 10 ... Impeller 11 ... Boss part 13 ... Feather part 15 ... · Upper shroud 17 · · · Lower shroud 17a · · · · inclined portion 17b · · · flat portion 30 · · · motor 31 · · · · · · · · · · · · Stator · Bearing holding portion 36 · · · Rotor magnet 40 · · · Circuit board 50 · · · · · · · 60 electronic components 100 · · · centrifugal fan O · · · central axis

Claims (10)

With the stator,
A rotor rotatable relative to the stator;
A motor having
An impeller fixed to the rotor and rotating with the rotor;
A circuit board electrically connected to the motor;
A casing for housing the motor, the impeller, and the circuit board;
A centrifugal fan having
The casing is
It has a lower casing provided with a substrate accommodation portion which is recessed axially downward and accommodates the circuit substrate,
The impeller is
A cylindrical boss fixed to the rotor;
A plurality of vanes disposed on the outer circumferential surface of the boss at intervals in the circumferential direction and extending radially outward;
An annular upper shroud that connects at least a portion of the upper side in the axial direction of the blade portion;
And an annular lower shroud that connects at least a portion of the lower side in the axial direction of the blade portion,
A centrifugal fan, wherein at least a part of the lower end surface of the blade portion axially faces the upper surface of the circuit board.   The centrifugal fan according to claim 1, wherein the radially outer edge of the lower shroud is disposed radially inward of the outer peripheral edge of the circuit board.   The lower casing has a flange portion extending radially outward from the outer peripheral edge of the substrate accommodation portion, and the height of the upper surface of the flange portion in the axial direction is equal to or less than the height of the upper surface of the circuit board. The centrifugal fan according to Item 1 or 2. The radially inner edge of the flange portion and the radially outer edge of the circuit board face each other with a predetermined gap therebetween,
The centrifugal fan according to claim 3, wherein a space above the circuit board in the axial direction is in communication with a space in the substrate accommodation portion located axially below the circuit board via the gap.   The centrifugal fan according to any one of claims 1 to 4, wherein at least a part of the lower end surface of the blade portion is axially opposed to the upper surface of the flange portion.   The centrifugal fan according to any one of claims 1 to 5, wherein the lower shroud has an inclined portion which inclines axially downward from the radially inner side to the outer side.   The centrifugal fan according to claim 6, wherein the lower shroud has a flat portion that is continuously formed radially outward of the inclined portion and extends along a plane perpendicular to the axial direction.   The radially outer edge of the lower shroud is located at the same radial position as the radially inner edge of the upper shroud, or radially inward of the radially inner edge of the upper shroud. The centrifugal fan according to any one of Items 1 to 7.   The centrifugal fan according to any one of claims 1 to 8, wherein the circuit board is mounted with an electronic component at a position radially outward of an edge radially outward of the lower shroud.   The said casing has an upper casing which covers the axial direction upper side of the said impeller, and the said upper casing has a circular inlet port which opposes the radial direction center part of the said impeller. Centrifugal fan as described in.

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